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5-HT3 receptor-dependent modulation of respiratory burst frequency, regularity, and episodicity in isolated adult turtle brainstems.

Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, 2015 Linden Drive, Madison, WI 53706, USA.
Respiratory Physiology & Neurobiology (Impact Factor: 1.97). 06/2010; 172(1-2):42-52. DOI: 10.1016/j.resp.2010.04.008
Source: PubMed

ABSTRACT To determine the role of central serotonin 5-HT(3) receptors in respiratory motor control, respiratory motor bursts were recorded from hypoglossal (XII) nerve rootlets on isolated adult turtle brainstems during bath-application of 5-HT(3) receptor agonists and antagonists. mCPBG and PBG (5-HT(3) receptor agonists) acutely increased XII burst frequency and regularity, and decreased bursts/episode. Tropisetron and MDL72222 (5-HT(3) antagonists) increased bursts/episode, suggesting endogenous 5-HT(3) receptor activation modulates burst timing in vitro. Tropisetron blocked all mCPBG effects, and the PBG-induced reduction in bursts/episode. Tropisetron application following mCPBG application did not reverse the long-lasting (2h) mCPBG-induced decrease in bursts/episode. We conclude that endogenous 5-HT(3) receptor activation regulates respiratory frequency, regularity, and episodicity in turtles and may induce a form of respiratory plasticity with the long-lasting changes in respiratory regularity.

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Available from: Julia R Wilkerson, Mar 15, 2015
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    • "Excitation of Post-I-cells may enhance episode termination and transform episodic breathing into singlet breathing. In isolated turtle brainstems , bath-applied 5HT 3 receptor agonist drugs increase singlet breathing while 5HT 3 receptor antagonist drugs increase episodic breathing (Bartman et al., 2010). Similarly, hypoxia-induced singlet breathing in intact turtles is abolished by pretreatment with 5HT 3 receptor antagonist drugs (S.M. Johnson, A.R. Krisp, M.E. "
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    Respiratory Physiology & Neurobiology 11/2014; DOI:10.1016/j.resp.2014.11.004 · 1.97 Impact Factor
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    • "4–5; Bartman et al., 2010). The respiratory rhythm within respiratory events in turtle brainstems appears to be regulated by a 5-HT 3 -dependent mechanism because 5-HT 3 receptor activation and blockade changes bursts/respiratory event (Bartman et al., 2010). The phenylephrine-induced decrease in bursts/respiratory event was not blocked by coapplication of α 1 and 5-HT 3 receptor antagonist drugs (Fig. 6A), suggesting that phenylephrine acts by an unknown mechanism (see discussion above). "
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